Magnetic switch

ABSTRACT

A switch includes a nonmagnetic container, a pair of spaced apart stationary contacts in the container, and a movable contact structure. The movable contact structure includes a cylindrical section movable by magnetic attraction between opposed extreme positions for engaging the movable contact structure with the stationary contacts, the movable contact structure tending to rebound from the stationary contacts. A cylindrical damper of nonmagnetic material is loosely mounted about the cylindrical section to move with the cylindrical section with such lost motion that they collide approximately as the movable structure begins to rebound.

United States Patent [72] Inventor Stanley R. Mitick Morrison, Ill. [2]] Appl. No. 882,043 [22} Filed Dec. 4, 1969 Division of Ser. No. 795,876, Feb. 3, 1969. [45] Patented Apr. 6, 1971 [73] Assignee General Electric Company [54] MAGNETIC SWITCH 5 Claims, 15 Drawing Figs.

[52] U.S. Cl 335/153, 200/166, 335/154 [51] Int. Cl ,.1I01h 51/28 [50] Field ofSearch 335/90, 104, 193, 151, 152, 154, 153,205;200/166 (H) [56] References Cited UNITED STATES PATENTS 2,039,630 5/1936 Burwell ..200/166(H)UX 3,033,965 5/1962 Wolaketal Primary Examiner-Bernard A. Gilheany Assistant Examiner- Roy N. Envall, J r.

Attorneys-John M. Stoudt, Radford M. Reams, Ralph E. Krisher, Jr., Oscar B. Waddell and Frank L. Neuhauser ZOO/166(H) p y-r Patented jApril 6, 1971 2 Sheets-Sheet 1 Patented April 6, 1971 3,573,686

2 Sheets-Sheet 2 FIG. 6c 6/ m FIG. 70 68 v INVENTOR. SKEW/6:9 Emma/z,

Attorney.

MAGNETIC swrrcn CROSS-REFERENCE TO RELATED APPLICATION This is a division of my copending application Ser. No. 795,876 filed Feb. 3, 1969.

BACKGROUND OF THE INVENTION This invention relates to magnetic switches.

Magnetic switches have come into widespread use. Such switches normally include a pair of spaced-apart stationary contacts and a movable contact structure which reciprocates between the stationary contacts under the influence of magnetic attraction. As the movable contact structure comes into engagement with one of the stationary contacts, it tends to rebound and bounce repeatedly. This causes arcing between the contacts which damages them and can also have deleterious effects on the device, apparatus, circuit or so forth electrically connected to the switch.

In many prior art switches the rebound or bounce was retarded by use of devices which kept the velocity of the movable contact as low as possible by frictional or inertial dampers. Such arrangements have not been completely satisfactory.

SUMMARY or THE INVENTION Therefore it is an object of the present invention to provide an improved magnetic switch.

It is yet another object of the present invention to provide an improved magnetic switch in which bounce of the movable contact structure is effectively damped.

It is still another object of this invention to provide such an improved magnetic switch in which bounce of the movable contact structure is damped by a collision type arrangement.

The invention, in one aspect thereof, provides a switch comprising a sealed container of nonmagnetic material. At leas one stationary contact is mounted in the container. A movable contact structure is mounted in the container for selective engagement with the stationary contact. The movable contact structure includes a section movable between extreme positions under the influence of magnetic attraction. A damper of nonmagnetic material is loosely mounted about the section of the movable contact structure for movement therewith with lost motion therebetween.

The above mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent and the invention itself will be better understood by reference to the following description, taken in conjunction with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a slightly enlarged perspective view of a magnetic switch incorporating one embodiment of the present invention;

FIG. 2 is an enlarged plan view of the switch of FIG. 1 with a portion of the housing broken away for purposes of illustratton;

FIG. 3 is an enlarged side elevational view of the switch of FIG. 1, with certain parts broken away and certain parts in section for purposes of illustration;

FIG. 4 is a view taken along the line 4-4 of FIG. 3;

FIG. 5 is a view taken along the line 5-5 of FIG. 3;

FIGS. 6a, 6b, 6c, 6d and 6e are diagrammatic presentations showing some of the relative positions of the magnet and damper of the switch of FIG. I, as the magnet moves in one direction between its extreme positions; and

FIGS. 7a, 7b, 7c, 7d and 7e are diagrammatic presentations, similar to FIGS. 6a-6e, showing certain relative positions of the magnet and damper as the magnet moves in the other direction between itsextreme positions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and particularly FIGS. 1 through 5, there is shown a new and improved magnetic switch 47 incorporating one embodiment of the present invention. The switch 47 includes a sealed housing 48 of suitable nonmagnetic material such as glass. Three leads 49, 50 and 51 extend through the housing at one end and are sealed therein. Within the housing a body of suitable insulation material 52 is formed around all three leads, giving them further structural stability and insuring that they are spaced apart so as to be electrically insulated. Leads 49 and 50 terminate in stationary contacts 53 and 54 respectively. Lead 51 extends axially beyond the contacts 53 and 54 and then is bent so as to have a termination 55 which is in axial alignment with the space between the stationary contacts 53 and 54. A U-shaped conductor 56 is mounted about the lead 51 and includes a lanced tongue 57 which is attached to the termination 55 so that the conductor 56 may pivot about the termination 55. One distal end of the conductor 56 extends between the stationary contacts 53 and 54 and is formed with a double contact structure 58, disposed selectively to engage the stationary contacts 53 and 54. The other distal end of the conductor 56 has its top portion cutaway to form a pair of opposed side arms 59 and 60. These arms firmly engage a generally cylindrical permanent magnet 61. Thus the lead 51, conductor 56, double contact 58 and permanent magnet 61 form a movable contact structure 62 with the permanent magnet 61 forming a distal portion or section thereof.

In order to make the termination 55 and lanced tongue 57 a stable pivot and to prevent excess vibration of the movable contact structure 62, a stabilizing member in the form of a leaf spring 63 is provided. A central bight portion 64 of the spring is attached to the termination 55 on the opposite side from tongue 57. A pair of arm portions 65 and 66 angle outwardly away from the central bight 64, with the arm portion 66 passing through an opening 67 in the conductor 56. As best seen in FIG. 5, the distal ends of the arms 65 and 66 each en gage the inner surface of the housing 48. This arrangement serves to center the termination 55 and tongue 57 for proper pivoting movement of the movable contact structure 62 during switch operations. At the same time it provides a fairly stiff yet somewhat resilient securing means preventing damage to the movable structure at such times as during shipping.

The magnet 61 moves, as a result of magnetic attraction, between the extreme position shown in FIG. 3, in which contact 58 engages stationary contact 54, and its other extreme position, in which contact 58 engages contact 53. This magnetic attraction is provided by the yoke or armature formed of ferromagnetic material and having spaced-apart fingers 24 and 25 disposed to be brought adjacent opposite sides of the housing 48 (see FIGS. 6 and 7). Thus, when finger 25 is moved adjacent the edge of the housing 48, the magnet 61 is attracted to the position shown in FIG. 3. By the same token, when the finger 24 is moved adjacent the housing 48, the magnet is attracted to its other position. Various details of one such yoke or armature are shown and described in my aforementioned application Ser. No. 795,876. It will be understood that it is not necessary to have the magnet 61 and cooperating armature in order to provide a switch which is selectively operated. For instance, the magnet 61 could be replaced by a cylindrical or flat armature of ferromagnetic material, to be moved by small permanent magnets, as is well known in the art.

With any of these general forms of magnetic switch constructions the movable contact structure tends to rebound or bounce. In the switch illustrated the contact 58 will tend to bounce from or rebound from the contacts 53 or 54 upon initial engagement as the magnet 61 is attracted between its extreme positions. If this rebound is not suitably controlled, the contacts will engage and then disengage or part several times before settling into a closed position. This tends to cause arcing between the contacts, which pits them, and may cause them to become welded together. It also could cause improper operation of a device or circuit connected to the contacts.

bounce in the switch. A generally cylindrical damper 68, of nonmagnetic material, is mounted loosely about the magnet 61 so that there is some space therebetween, as illustrated at 69. In the exemplification the damper 68 includes a cylindrical sidewall 680 which fits along the magnet 61 and an end wall 68b which extends across the free end of the magnet. This cup shape of the damper prevents the damper moving to the left along the magnet. Also the sidewall 68a is longer than the distance from the end of the magnet 61 to the end of the housing 48. This prevents the damper coming off the end of the magnet during shipping or other handling. For operation, the switch preferably is mounted with the distal end of the magnet 61 elevated at least slightly relative to its pivot. It may even be mounted so that the movable contact structure 62 pivots about a vertical axis. With this arrangement gravity assures proper contact between the magnet and the damper. As the magnet moves between its extreme positions, it will cause the damper to move with it; however, there will be lost motion between the magnet and the damper. This lost motion results in an operation such that, after the movable contact structure reaches its extreme position, with contact 58 engaging either contact 53 or 54, and is rebounding or bouncing, the damper 68 will collide with the magnet. The best damping results are obtained by sizing the magnet and damper to provide a degree of lost motion between them such that the collision between them occurs approximately as the movable contact structure begins to rebound.

FIGS. 6a-6e and 7a-7e are somewhat exaggerated diagrammatical presentations of certain relative positions between the magnet and the damper of a switch such as that illustrated in FIGS. 1 through when it is mounted with the distal end of the magnet 61 slightly elevated with respect to its pivot. FIG. 6a shows the magnet and damper at rest with the armature finger 25 closely adjacent to the switch. When the armature moves from the position shown in H6. 6a to that shown in FlG. 6e, the magnet is drawn downwardly and moves through the damper to engage its lower portion, as viewed in FIG. 61;. FIG. 6c shows the situation at some time when contact 58 is in midposition (that is, not engaging either of the fixed contacts 53 and 54). At this time the magnet is driving the damper. In the view of HG. 6dthe contact 58 has engaged the contact 53 and the magnet is decelerating. While it still has some velocity, that velocity is small compared to the velocity of the damper, which has not encountered any decelerating force up to this point. FIG. 62 shows the situation at the point where, due to the resiliency of the movable contact structure, the magnet is moving up as a result of the energy stored during deceleration. The damper is still moving down so that the magnet and the damper collide or engage. This collision dissipates at least a large portion of the energy of the movable contact structure. There may be a small number of collisions as the magnet and the damper tend to vibrate about the collision point; however, most of the energy is dissipated by the first collision.

It will be understood that, with an ideal design of elements the motion of the magnet and thus the movable contact structure would be stopped completely on the first impact. However, due to various structural and material limitations this may not always be possible. However, in any event, the damper may be made much more efficient than prior art devices which relied upon some resistance or friction for keeping the speed of the movable contact slow. It is quite important to provide correct differences in diameter between the damper and the corresponding distal portion of the moving contact structure so that collision takes place approximately as the corresponding portion of the movable contact structure, in this case the magnet, begins rebounding. Also maximum damping will be obtained by making the damper as contact 58 from the contact 53 to the contact 54.

Referring now to FIG. 1 and completing the description of the switch 47, three conductors, such as those illustrated at 70, 71 and 72 may be attached to the leads 49, 50 and 51 respectively by some suitable means such as welding and then enclosing the connections within a protection covering or cap such as that shown at 73.

While, in accordance with the Patent Statutes, l have described what, at present is considered to be the preferred embodiments of my invention, it will be obvious to those skilled in the art that numerous changes and modifications may be made therein without departing from the invention, and it is therefore aimed in the appended claims to cover all equivalent variations as fall within the true spirit and scope of the invention.

I claim:

1. A switch comprising a sealed container of nonmagnetic material; at least one stationary contact mounted in said container; a movable contact structure mounted in said container for selective engagement with said stationary contact; said movable contact structure including a section movable between opposed extreme positions under the influence of magnetic attraction, one of said extreme positions corresponding to engagement of said movable contact structure with said at least one stationary contact; said movable contact structure tending to rebound upon reaching said one of said extreme positions; and a damper of nonmagnetic material loosely mounted about said section for movement with said section with such lost motion therebetween that said section of said movable contact'structure and said damper collide approximately as said movable contact structure begins to rebound.

2. The switch as set forth in claim 1 including a pair of spaced-apart stationary contacts; said movable contact structure selectively engaging a different one of said stationary contacts when said movable contact structure is in a different one of its extreme positions; said damper being loosely mounted upon said section of said movable contact structure with such lost motion therebetween that said damper will collide with said section approximately as said movable contact structure begins to rebound from either of its extreme positions. 1

3. A switch comprising a sealed container of nonmagnetic material; a pair of spaced-apart stationary contacts mounted within said container; a movable contact structure pivotally mounted within said container for selective engagement with each of said stationary contacts; said movable contact structure including a generally cylindrical section movable between opposed extreme positions under the influence of magnetic attraction for selectively moving said movable contact structure into engagement with each of said stationary contacts, said movable contact structure tending to rebound from engagement with each of said stationary contacts; and a generally cylindrical damper of nonmagnetic material loosely mounted about said cylindrical section for movement therewith and with lost motion therebetween such that said damper and said cylindrical sectionwill collide approximately as said movable contact structure begins to rebound.

4. The switch as set forth in claim 3 wherein said cylindrical section is a permanent magnet.

5. The switch as set forth in claim 3 wherein said magnet forms a distal end of said movable contact structure and wherein said damper is in the form of a cup-shaped member mounted loosely over the free end of said magnet. 

1. A switch comprising a sealed container of nonmagnetic material; at least one stationary contact mounted in said container; a movable contact structure mounted in said container for selective engagement with said stationary contact; said movable contact structure including a section movable between opposed extreme positions under the influence of magnetic attraction, one of said extreme positions corresponding to engagement of said movable contact structure with said at least one stationary contact; said movable contact structure tending to rebound upon reaching said one of said extreme positions; and a damper of nonmagnetic material loosely mounted about said section for movement with said section with such lost motion therebetween that said section of said movable contact structure and said damper collide approximately as said movable contact structure begins to rebound.
 2. The switch as set forth in claim 1 including a pair of spaced-apart stationary contacts; said movable contact structure selectively engaging a different one of said stationary contacts when said movable contact structure is in a different one of its extreme positions; said damper being loosely mounted upon said section of said movable contact structure with such lost motion therebetween that said damper will collide with said section approximately as said movable contact structure begins to rebound from either of its extreme positions.
 3. A switch comprising a sealed container of nonmagnetic material; a pair of spaced-apart stationary contacts Mounted within said container; a movable contact structure pivotally mounted within said container for selective engagement with each of said stationary contacts; said movable contact structure including a generally cylindrical section movable between opposed extreme positions under the influence of magnetic attraction for selectively moving said movable contact structure into engagement with each of said stationary contacts, said movable contact structure tending to rebound from engagement with each of said stationary contacts; and a generally cylindrical damper of nonmagnetic material loosely mounted about said cylindrical section for movement therewith and with lost motion therebetween such that said damper and said cylindrical section will collide approximately as said movable contact structure begins to rebound.
 4. The switch as set forth in claim 3 wherein said cylindrical section is a permanent magnet.
 5. The switch as set forth in claim 3 wherein said magnet forms a distal end of said movable contact structure and wherein said damper is in the form of a cup-shaped member mounted loosely over the free end of said magnet. 